Error message: 

Unable to cast object of type 'Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Types.PdfInt' to type 'Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Elements.MarkedContents.StructAttributeObject'.

InvalidCastException is thrown when importing a document with a structure element with an indirect reference to an integer value.

InvalidCastException: 'Unable to cast object of type 'Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Types.PdfInt' to type 'Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Elements.MarkedContents.StructElementObject'.'

When you register a font in an ASP.Core project and in a static constructor, the generated PDF document will have this font only the first time you load the web page. Refreshing the page will generate the PDF document but the fonts will be lost.

Note: This worked in the previous version  2025.2.701.

Part of the stack trace: 

System.OutOfMemoryException: Insufficient memory to continue the execution of the program.
   at System.Text.StringBuilder.ExpandByABlock(Int32 minBlockCharCount)
   at System.Text.StringBuilder.AppendWithExpansion(Char value)
   at System.Text.StringBuilder.Append(Char value)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Utilities.CrossReferenceCollectionReader.GetAllText(Reader reader, Int64 minOffset, Int64 maxOffset)
   at Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Utilities.CrossReferenceCollectionReader.FindAllObjectOffsets(Reader reader, Dictionary`2 tokenToOffsets, Int64 minOffset, Int64 maxOffset)

Solution - use the ExpandableMemoryStream for the import instead.

PDF content:

Exported text content:

The current implementation of IDisposable implements a simple Dispose method which releases the inner stream resource. However, if the PdfStreamWriter instance is not disposed explicitly by calling Dispose() or by surrounding it in "using" clause, then the inner Stream resource is not Disposed as well. The same applies for PdfFileSource class.

We should implement the IDisposable pattern in a way that the GC disposes the inner stream if needed when collecting the PdfStreamWriter/PdfFileSource class instances.

Corrupted document when exporting "Courier New" subset.

Workaround - fully embed the font:

var pdfFormatProvider = new PdfFormatProvider();
pdfFormatProvider.ExportSettings.FontEmbeddingType = FontEmbeddingType.Full;